In my original application, Ser. No. 304,412, I disclosed an embodiment wherein the vacuum attachment includes an annular chamber with a generally triangular cross-section, of which a radially inner, upper apex was intercalated axially between a rigid flange and a resilient ring mounted on the abrading machine. This permitted some rocking limited and axial excursion of the chamber with respect to the abrader.
My next application, Ser. No. 362,855 disclosed two features I believed to be improvements on the original design. The mounting of the chamber was changed, the resilient ring and intercalation were replaced by securing an annular, flexible web at its outer extent to the chamber and at its inner extent to a mounting flange provided on the abrading machine. The hose connection for communicating vacuum to the chamber was moved to permit the chamber to be moved through 360 degrees with respect to the abrading machine.
During the prosecution of the foregoing applications and their Canadian and other foreign counterpart applications, the applicant has become aware of the following prior patents:
______________________________________ United States: Thompson 1,700,118 January 22, 1929 Vidal 2,168,692 August 8, 1939 Hageal et al 2,618,008 November 18, 1952 Subonovich 3,256,648 June 1966 Wason 3,330,537 July 11, 1967 Hyde 3,375,540 April 2, 1968 Jones 3,468,076 September 23, 1969 Danzig 3,644,960 February 29, 1972 Oimoen 3,673,744 July 4, 1972 Hughes 3,686,707 August 29, 1972 Vinella 3,701,221 October 31, 1972 Hutchins 3,824,745 July 23, 1974 Foreign: DBP (Germany) 846,215 August 11, 1952 DBP (Germany) 1,085,064 December 29, 1960 ______________________________________
In the automotive industry, welded seams, primer and other coatings are subjected to abrading action by hand-held machines, preparatory to further finishing operations. In many plants, the work has customarily been bathed in a water spray during abrading, but environmental concerns over disposal of the contaminated waste water has lead to the coversion of many plants from wet abrading to dry abrading for these tasks.
Widespread conversion to dry abrading is dependent upon the simultaneous solution of an environmental health and production problem: dry abrading releases particles of the abraded material into the air. Some of the material has been determined to represent a danger to health, if breathed. In addition, a dusty atmosphere is unwanted in an area where finishes are being applied, because some will settle upon automotive finishes which have just been applied, and spoil their smooth appearance.
Various hoods and vacuum chambers have been proposed by others for use with other scrubbing, cleaning, cutting or abrading equipment used in other contexts.
For instance, floor scrubbing machines have been provided with hoods for sucking spent cleaning solution and incorporated dirt from around a rotating scrubbing brush. A number of problems present in the automotive environment are absent in the floor cleaning environment. For example, the floor is flat and is addressed flatwise by the brush so the dirty solution is always being flung outwards along the same annular path. A chamber can be confidently fixed with respect to the floor cleaner to intercept that path. However, an automotive body has many curved surfaces, is often addressed at an acute angle by the abrading disk, and the disk often needs to be moved off the work surface at an edge, in order to abrade right to that edge. Accordingly, a vacuum chamber which is fixed on the abrading machine will often miss the path of the abraded material being flung off the work surface. And when the abrader is moved part-way off an edge, a vacuum chamber that consists of a hood which encloses the back and outer sides of the abrader, would loose effectiveness, because so large a part of its open underside would be off the work surface and open to the air.
Furthermore, whereas a floor being cleaned remains underfoot, an automotive body being finished needs attention to e.g., roof, quarter panel and trunk lid portions that are disposed at various heights and angular dispositions relative to the worker. Accordingly, whereas the connection of the vacuum line to the chamber may represent no obstacle to the worker using a floor cleaner, an automotive body finisher can find his working hindered by the vacuum hose.
While the present inventor sees a primary application of the invention in the automotive field, that application is by no means exclusive. It may find use in analogous instances where there is a need to prevent material which has been abraded from a surface from contaminating the air, from fouling the worker or the work area or from interfering with continued abrading work.